def test_apply_SWAP_full_swap(self):
qc = QC(3, 0, noise=True, pg=0.1)
qc.CNOT(0, 1)
qc.CNOT(1, 0)
qc.CNOT(0, 1)
qc2 = QC(3, 0, noise=True, pg=0.1)
qc2.SWAP(0, 1, efficient=False)
np.testing.assert_array_almost_equal(
qc.total_density_matrix()[0].toarray(),
qc2.total_density_matrix()[0].toarray())
def test_measure_first_qubit_bell_state_one(self):
qc = QC(2, 1)
qc.CNOT(0, 1)
qc.measure(0, outcome=1, basis="Z")
correct_result = np.array([[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0],
[0, 0, 0, 1]])
np.testing.assert_equal(qc.total_density_matrix()[0].toarray().real,
correct_result)
def test_measure_first_N_qubit(self):
# Initialise system in |+0> state, CNOT on 2nd qubit and measure |+> on first qubit
qc = QC(2, 1)
qc.CNOT(0, 1)
qc.measure_first_N_qubits(1, measure=0)
correct_result = np.array([[0.5, 0.5], [0.5, 0.5]])
np.testing.assert_array_equal(qc.total_density_matrix()[0].toarray(),
correct_result)
# Initialise second system also in |+0>, CNOT on 2nd qubit and measure |-> on first qubit
qc2 = QC(2, 1)
qc2.CNOT(0, 1)
qc2.measure_first_N_qubits(1, measure=1)
correct_result_2 = np.array([[0.5, -0.5], [-0.5, 0.5]])
np.testing.assert_array_equal(qc2.total_density_matrix()[0].toarray(),
correct_result_2)
def test_measure_first_qubit_bell_state_minus(self):
# Initialise second system also in |+0>, CNOT on 2nd qubit and measure |-> on first qubit
qc = QC(2, 1)
qc.CNOT(0, 1)
qc.measure(0, outcome=1)
correct_result = 1 / 4 * np.array([[1, -1, -1, 1], [-1, 1, 1, -1],
[-1, 1, 1, -1], [1, -1, -1, 1]])
np.testing.assert_array_almost_equal(
qc.total_density_matrix()[0].toarray().real, correct_result)
def test_two_qubit_gate_error(self):
qc = QC(2, 0, noise=True, pg=0.01)
qc.CNOT(0, 1)
expected_density_matrix = np.array([[(1 - (0.01 * 12 / 15)), 0, 0, 0],
[0, 0.04 / 15, 0, 0],
[0, 0, 0.04 / 15, 0],
[0, 0, 0, 0.04 / 15]])
np.testing.assert_array_almost_equal(
qc.total_density_matrix()[0].toarray().real,
expected_density_matrix)
def test_apply_SWAP_efficient_swap(self):
qc = QC(3, 0, noise=True, pg=0.1, pn=0.1)
qc.create_bell_pair(1, 2)
qc._uninitialised_qubits.append(0)
# SWAP is equal to three CNOT operations
qc.CNOT(1, 0)
qc.CNOT(0, 1)
qc.CNOT(1, 0)
# Qubit 1 is now uninitialised due to swapping. Measure it such that it disappears from the density matrix
qc.measure(1)
qc2 = QC(3, 0, noise=True, pg=0.1, pn=0.1)
qc2.create_bell_pair(1, 2)
qc2._uninitialised_qubits.append(0)
qc2.SWAP(1, 0, efficient=True)
# Measurement of qubit 1 is not necessary, since the density matrices are not fused with the efficient SWAP
np.testing.assert_array_almost_equal(
qc.get_combined_density_matrix([0])[0].toarray(),
qc2.get_combined_density_matrix([0])[0].toarray())